Field of the Invention
The present invention relates generally to cams. Particularly, the invention relates to adjustable cams designed for exercise equipment
Description of Related Art
In this country there is a concern about the growing obesity rate and counteracting an increasingly sedentary lifestyle. More people are going to the gym and finding exercise machines a safer alternative to free weights. Exercise machines are becoming more sophisticated, and gyms are buying more machines to focus on different muscle groups. However, there has not been a lot of work in fine-tuning individual exercise machines to allow a user to alter the strength curve (i.e., how much weight is applied at each point in the movement).
U.S. Pat. No. 4,982,956 to Lapcevic discloses adjusting the strength curve by rotating the cam about the machine shaft. Lapcevic also discloses that a supplemental cable receiving mechanism is needed to keep the cable taut.
U.S. Patent Publication No. 2003/0092540 to Gillen discloses a range limiting device that uses multiple cam followers and a defined track on the exercise frame to adjust the cam. Gillen also discloses tracking the belt to keep the belt tight.
U.S. Pat. No. 5,722,921 to Simonson discloses a range limiting device like Gillen, where the exercise input arm is attached to the cam and works with the cam to change the strength curve. Like Lapcevic, Simonson needs a supplemental cable or belt receiving mechanism to keep the belt tight.
U.S. Pat. No. 5,356,360 to Johns is similar to Simonson but does not use a track mechanism attached to the frame to resist backward movement of the cam and to control cable slack. Rather, Johns uses a linkage to control cable slack. Further, like the other prior art, Johns discloses rotating the cam around the input shaft to achieve the strength curve.
U.S. Pat. No. 5,102,121 to Salow discloses using a supplemental cable receiving device where the cam profile rotates around the main axis for strength curve.
The exercise cams of the prior art use supplemental cables or belts, rather than attaching the belt to the cam directly. Further, the prior art discloses adjusting the strength curve by rotating the cam around the machine shaft in a single arc, which limits the adjustability of the cam in the exercise machine.
The need exists for an exercise machine where the belt from the weight stack attaches directly to the cam, and where the cam rotates about multiple arcs.